Hi Sakis,
It was enjoyable reading through the different comparisions of amps. I understand that you spend most of the time repairing amps that customers' bring in. Have you had the chance to compare the P3A to other "highly" regarded amps ? For example :
1. JLH 1969 original
2. Pass F5 (sorry, I do realise you are not a Class A amp guy
)
3. Hugh's NAKSA/AKSA amp
4. Behringer EP1500
5. P101 Rod's 200W mosfet amp
Cheers~
Dinesh
It was enjoyable reading through the different comparisions of amps. I understand that you spend most of the time repairing amps that customers' bring in. Have you had the chance to compare the P3A to other "highly" regarded amps ? For example :
1. JLH 1969 original
2. Pass F5 (sorry, I do realise you are not a Class A amp guy
)3. Hugh's NAKSA/AKSA amp
4. Behringer EP1500
5. P101 Rod's 200W mosfet amp
Cheers~
Dinesh
hello chl ....
yeap ...that is correct ..i am not a class A guy ... i listen to music from my amps a minimum of 8 hours per day and i wouldnt mind burning 300 or 500 w per chanel to do that as long as it sounded nice ...or that nice to deserve the idea ...
my P 3A hasnt been on the race next to none of these amplifiers only one of class A was standing next to it the AC magnum class A where the p3A ( as described an as made ) outperformed the magnum from the first second
as about Hugh's amps i belive that are perfectly designed and made but never had the previlge to have one ( yet)
the behringer Ep1500 if its in the same theory of the 2500 but simply lower power cannot even be compaired to the P3a since topology na principal of operation is by far tto diferent ... yet again the EP 1500 is a nice amp but the designers have focused on as much power is possible and as much stability is possible ... from pro expirience i can tell you that the made is excellent sub woofer amplifier ... but not realy the best for hifi PA
now P101 is an amp that i ve made got the original board and made everything by the book so yes its a powerfull amp that produces exactly as said yet remains musical and in the hifi are or above ...
P101 next to P3A if you skip the the power issues i would go for the P3A again by far ...the sziklai topology eventhough suffers from stability issues if not designed properly remains more musical than classic EFP amplifier that on the other hand are more precise and acurate
the best area of the P3a is the first few Watts that are short od class A watts but still the next in midle power that comes out of the amp is still one opf the best i worked with
this then is a question of choise ... that depents a lot on the music you listen to
here is my 2 cents in your question ...before you make your choise remeber to read that the p3A the way i make it has a few changes (minor ) than the standard version ...Since class AB amplifier is no more than 10 topologies (at this range of power ) remember also that all these small details and the way implmeneted make a lot of diference ...
Look ta DX amplifiers in the forum ... extensive and long threads where every lilte small detail has been worked out and belive me that these details can make a totally diferent amplifier than the first schematic you ve seen ...
yeap ...that is correct ..i am not a class A guy ... i listen to music from my amps a minimum of 8 hours per day and i wouldnt mind burning 300 or 500 w per chanel to do that as long as it sounded nice ...or that nice to deserve the idea ...
my P 3A hasnt been on the race next to none of these amplifiers only one of class A was standing next to it the AC magnum class A where the p3A ( as described an as made ) outperformed the magnum from the first second
as about Hugh's amps i belive that are perfectly designed and made but never had the previlge to have one ( yet)
the behringer Ep1500 if its in the same theory of the 2500 but simply lower power cannot even be compaired to the P3a since topology na principal of operation is by far tto diferent ... yet again the EP 1500 is a nice amp but the designers have focused on as much power is possible and as much stability is possible ... from pro expirience i can tell you that the made is excellent sub woofer amplifier ... but not realy the best for hifi PA
now P101 is an amp that i ve made got the original board and made everything by the book so yes its a powerfull amp that produces exactly as said yet remains musical and in the hifi are or above ...
P101 next to P3A if you skip the the power issues i would go for the P3A again by far ...the sziklai topology eventhough suffers from stability issues if not designed properly remains more musical than classic EFP amplifier that on the other hand are more precise and acurate
the best area of the P3a is the first few Watts that are short od class A watts but still the next in midle power that comes out of the amp is still one opf the best i worked with
this then is a question of choise ... that depents a lot on the music you listen to
here is my 2 cents in your question ...before you make your choise remeber to read that the p3A the way i make it has a few changes (minor ) than the standard version ...Since class AB amplifier is no more than 10 topologies (at this range of power ) remember also that all these small details and the way implmeneted make a lot of diference ...
Look ta DX amplifiers in the forum ... extensive and long threads where every lilte small detail has been worked out and belive me that these details can make a totally diferent amplifier than the first schematic you ve seen ...
service technics SU-V450
never repaired any of these before ...Very nice amp based on the powerfull SVI 3204 IC which is by far better from older stk cousins
the quality of built inside is actually very high and materials used are the best of quality .Seems also that arengements inside signal routing and cable rooting is done in the besto possible way ..
For sure this is not a high end design but remains a very good production comercial amplifier ... Bandwidth is very fine tone controls are elegant have also defeat switch and source direct control .
with one active source all sound pretty fine there is very clean sound deep with soundstage ... on the negative side i could put the choise of Q and mid frequency of the treble control that works mostly like a presence control than a treble control .... still this is done very gently ...
enjoy some pictures especially the ones that hydraulics meet electronics
(specific amp has copper pipe filed with freon (?) or something else to transfer the heat from the back of the ic to the heatsink ... nice !!
kind regards sakis
never repaired any of these before ...Very nice amp based on the powerfull SVI 3204 IC which is by far better from older stk cousins
the quality of built inside is actually very high and materials used are the best of quality .Seems also that arengements inside signal routing and cable rooting is done in the besto possible way ..
For sure this is not a high end design but remains a very good production comercial amplifier ... Bandwidth is very fine tone controls are elegant have also defeat switch and source direct control .
with one active source all sound pretty fine there is very clean sound deep with soundstage ... on the negative side i could put the choise of Q and mid frequency of the treble control that works mostly like a presence control than a treble control .... still this is done very gently ...
enjoy some pictures especially the ones that hydraulics meet electronics
(specific amp has copper pipe filed with freon (?) or something else to transfer the heat from the back of the ic to the heatsink ... nice !!
kind regards sakis
Attachments
Hi Sakis,
thanks for the reply. I will be building a few amps, P3A included and will post some findings here too.
My current reference amp : Aussieamplifier Nxv200 DC coupled stereo amplifier
Future amps to build : (won't take long because I start uni in January)
-P3A with DoZ preamp
- Pass F5 class A
- Carlos's DX Blame ST
- JLH 1969 original
Regards,
-D-
thanks for the reply. I will be building a few amps, P3A included and will post some findings here too.
My current reference amp : Aussieamplifier Nxv200 DC coupled stereo amplifier
Future amps to build : (won't take long because I start uni in January)
-P3A with DoZ preamp
- Pass F5 class A
- Carlos's DX Blame ST
- JLH 1969 original
Regards,
-D-
hello ... thanks for your reply .... include in your projecs the B1 buffer with the P3A make a wonderfull set one of the best i ve ever listen to
it will be also very nice to state somewhere full details of your builts and comparsion between them ( once i was trying to see where exactly is located the diferences between the standard Dx amp and the blame st ...but the @*?/ thread is too long to read )
with respect sakis
it will be also very nice to state somewhere full details of your builts and comparsion between them ( once i was trying to see where exactly is located the diferences between the standard Dx amp and the blame st ...but the @*?/ thread is too long to read )
with respect sakis
Complete P3A with P37A DoZ preamp
Hi sakis n all,
I have completed Rod Elliot's P3A and P37A preamp build in a single chassis, aka integrated amp. Some features :
11,000 uF per channel formed with 5 X 2,200uF caps. Each cap has a 0.1uF MKT snubber (ultra low impedance PS). 35A 400V bridge rectifier used.
Transformer : 500VA dual secondary 18V - drastically lowering my power =(
Grounding - Power supply ground connected to chassis via single wire. IEC ground pin connected to chassis (surely!)
Vishay 50K log pot
Preamp P37A module : Input cap - 3.3uF Mundorf M-Cap
All carbon film resistors (finally reduced some high freq
agressiveness)
Output cap removed, replaced with wire link
P3A amp module : Input cap - 1uF Wima MKP
Power trans : MJL21193/21194 from Farnell
KOA 1% Metal film resistors (Farnell)
A small 20VA transformer delivers the power to the preamp PS PCB and also powers 2 small CPU fans. One blows on the large trans, the other on heatsink.
Bitumen damping on EI transformer, as well as all the underside of PCB's.
I am in love with this amp. Dead silent, no hiss or whatever.
It trancends above the level of my other amps.
Midrange is ultra transparent, electrostatic like. Bass thunders, dynamics are frightening. Highs are soft, tube like. Best way to describe : lifelike sound.
Thanks Sakis. Very nice amp recommendation.
Next amp : Carlos DX Blame ES
Will be interesting to see how it compares !
Hi sakis n all,
I have completed Rod Elliot's P3A and P37A preamp build in a single chassis, aka integrated amp. Some features :
11,000 uF per channel formed with 5 X 2,200uF caps. Each cap has a 0.1uF MKT snubber (ultra low impedance PS). 35A 400V bridge rectifier used.
Transformer : 500VA dual secondary 18V - drastically lowering my power =(
Grounding - Power supply ground connected to chassis via single wire. IEC ground pin connected to chassis (surely!)
Vishay 50K log pot
Preamp P37A module : Input cap - 3.3uF Mundorf M-Cap
All carbon film resistors (finally reduced some high freq
agressiveness)
Output cap removed, replaced with wire link
P3A amp module : Input cap - 1uF Wima MKP
Power trans : MJL21193/21194 from Farnell
KOA 1% Metal film resistors (Farnell)
A small 20VA transformer delivers the power to the preamp PS PCB and also powers 2 small CPU fans. One blows on the large trans, the other on heatsink.
Bitumen damping on EI transformer, as well as all the underside of PCB's.
I am in love with this amp. Dead silent, no hiss or whatever.
It trancends above the level of my other amps.
Midrange is ultra transparent, electrostatic like. Bass thunders, dynamics are frightening. Highs are soft, tube like. Best way to describe : lifelike sound.
Thanks Sakis. Very nice amp recommendation.
Next amp : Carlos DX Blame ES
Will be interesting to see how it compares !
Attachments
well ... i am back from the dead ...been away for almost 2 months with various company problems but now this is all in the past ....
ok here it is ... Nice of you for making the P3A but personaly i would a few thngs in an other way ... most of it should be wiring issus and make a construction that is better organized ...your powe supply eventhough could work properly looks terrible and that would also apply to your wiring and shielding of input cables
the pot you selected to use is a terrible you should look for something better that will ensure more linear tracking and most of all equal signal for both ch .
Finaly i dont belive that any of the above will make audible diference except the pot but will make your amp look and work better
other than the above all the rest looks fine .... so happy listening for you ... and i ecpect your comparsion with any other amp soon .
ok here it is ... Nice of you for making the P3A but personaly i would a few thngs in an other way ... most of it should be wiring issus and make a construction that is better organized ...your powe supply eventhough could work properly looks terrible and that would also apply to your wiring and shielding of input cables
the pot you selected to use is a terrible you should look for something better that will ensure more linear tracking and most of all equal signal for both ch .
Finaly i dont belive that any of the above will make audible diference except the pot but will make your amp look and work better
other than the above all the rest looks fine .... so happy listening for you ... and i ecpect your comparsion with any other amp soon .
I have to apologize to all the people reading this thread since i have been away too long ...
we had local election in my country and that means 3 weeks of endless hi power road shows and screaming ... me and all the people that work for me are simply exausted .... we need a few days to calm down and we will be right back with you
thanks to all !!! for the comments and opinion that is shared in this thread
kind regards sakis
we had local election in my country and that means 3 weeks of endless hi power road shows and screaming ... me and all the people that work for me are simply exausted .... we need a few days to calm down and we will be right back with you
thanks to all !!! for the comments and opinion that is shared in this thread
kind regards sakis
Last edited:
Hi Sakis n guys,
I sort of forgot abt this thread =S
THis is the first amp I ever made and completed!
Regarding the pot, it turned out to be ok, tracking is very good and I have a very stable image centre. No hum/hiss, superb performing amp. This P3A is back in my main listening area as it somehow matches my speakers the best. Bass is full, deep and tight, midrange very clear but a touch thin - that is ok because my 8'' cones sound too warm if valve amps are used. Components are dirt cheap, yet the sound rivals some of the best amps I've heard. Here are the list of amps I own (in no particular order) :
1. Aussie Amps NXv200 (utterly drop dead neutral, huge dynamics and bass control)
2. Behringer EP1500 (prominent midbass, clear midrange, average highs)
3. Class D TK2050 monoblocks (laid back, artificially sounding soft highs, decent bass)
4. Goldmund Telos 250 (Dreaming about owning it. Shockingly lively, massive sound)
5. 3W SE Mosfet Class A (extremely musical but lacks clarity and power)
6. Carlos's DX Blame ES (musical, smooth, dynamic, prominent deep bass authority)
7. Krell KSA 100 Pure Class A (crystal clear, incredible bass control but slightly analytical)
8. TDA 2050 chip amp (superb imaging, average bass)
9. LM3886 chip amp (superb treble but not as involving as the other amps)
All amps tested on my large 2 ways speakers.
Sonically the top 3 are P3A, Aussie Amps NXv200 and Blame ES.
For obvious reasons, the Telos 250 will not be included. =P
I sort of forgot abt this thread =S
THis is the first amp I ever made and completed!
Regarding the pot, it turned out to be ok, tracking is very good and I have a very stable image centre. No hum/hiss, superb performing amp. This P3A is back in my main listening area as it somehow matches my speakers the best. Bass is full, deep and tight, midrange very clear but a touch thin - that is ok because my 8'' cones sound too warm if valve amps are used. Components are dirt cheap, yet the sound rivals some of the best amps I've heard. Here are the list of amps I own (in no particular order) :
1. Aussie Amps NXv200 (utterly drop dead neutral, huge dynamics and bass control)
2. Behringer EP1500 (prominent midbass, clear midrange, average highs)
3. Class D TK2050 monoblocks (laid back, artificially sounding soft highs, decent bass)
4. Goldmund Telos 250 (Dreaming about owning it. Shockingly lively, massive sound)
5. 3W SE Mosfet Class A (extremely musical but lacks clarity and power)
6. Carlos's DX Blame ES (musical, smooth, dynamic, prominent deep bass authority)
7. Krell KSA 100 Pure Class A (crystal clear, incredible bass control but slightly analytical)
8. TDA 2050 chip amp (superb imaging, average bass)
9. LM3886 chip amp (superb treble but not as involving as the other amps)
All amps tested on my large 2 ways speakers.
Sonically the top 3 are P3A, Aussie Amps NXv200 and Blame ES.
For obvious reasons, the Telos 250 will not be included. =P
one of the things i would trully like to try is to sent over my amplifier to test next to ....i mean if a "dirt cheap" version of the P3a managed so well i wonder mine that features so many goodies will be by far better ...
shiping cost will be probably out of the question ha ha ha ha
fine though happy listening
shiping cost will be probably out of the question ha ha ha ha
fine though happy listening
service HAFLER 9270
just finished working with an 9270 HAFLER ... very rowbust machine ...well builted
a few caps to be replaced Nothing damaged though replaced also a couple of trimers ( small nice pihers work fine but still i wanted somethimg better for this machine )
the actuall damage was only dirty but so very dirty pots .... surprizinglly this pots was set to midle sometime ago like 10 years and never had to be mooved again ... Obviously stoped working...nothing more than a psssiiiit of spray on them
Again i will say that these pots also looked dirt cheap for this type of amp ....often parts like that are selected cause sound nice but trully they look like the pots you find in 1$ chinese transistor radios ...any way
Next to the P3A hafler was by far more powerfull ( add to this that was preamp hungry ) .... high was surprinzingly clean and clear without being too much or too litle ...midle was thin had the impression that the all midle was one step behind ...As about bass i was left with the impression that was not enough low next to the P3 ... it sounded like there was some subsonic filter activated in the Hafler ...
a very nice amp i would say ....
kind regards sakis
just finished working with an 9270 HAFLER ... very rowbust machine ...well builted
a few caps to be replaced Nothing damaged though replaced also a couple of trimers ( small nice pihers work fine but still i wanted somethimg better for this machine )
the actuall damage was only dirty but so very dirty pots .... surprizinglly this pots was set to midle sometime ago like 10 years and never had to be mooved again ... Obviously stoped working...nothing more than a psssiiiit of spray on them
Again i will say that these pots also looked dirt cheap for this type of amp ....often parts like that are selected cause sound nice but trully they look like the pots you find in 1$ chinese transistor radios ...any way
Next to the P3A hafler was by far more powerfull ( add to this that was preamp hungry ) .... high was surprinzingly clean and clear without being too much or too litle ...midle was thin had the impression that the all midle was one step behind ...As about bass i was left with the impression that was not enough low next to the P3 ... it sounded like there was some subsonic filter activated in the Hafler ...
a very nice amp i would say ....
kind regards sakis
Last edited:
some more update on this
through the times i had to work with various amps and some of them feature input imp from 10 Kohm till 100 kohm obviously the ones that are lower than 47 kohms will be more preamp hungry and obviously when used with a passive pot in the input the variations of imp will probably effect dynamics ...
been testing the P3a with a classic preamp from esp pages ...that will be a pot and a 5532 circuit ( with the pot in the input of the ic ) and the results where average ....configuration like that doesnt do any good to the P3A ...actually it makes it worst .... nurve and dynamics is improved but you loose soundstage while both ends high and low are worst ...
So B1 is the one and only solution ??? dont know i am looking in to it ... it has been an issue that we talkked about since the combination of P3A and B1 worked like a charm and we thought about to looking in to any other active preamp schematic ( descrete) that could provibe all ...bandwidth ,dynamics ,transparecy and gain ....
some more approach regarding this will come in a few days and one of them is to listen something from the OPA series in the same configuration that was never tested before
will see
thank you all
kind regards sakis
--- hello everybody
havent been updating the thread for Quiet a long time ... sorry to say i am way to busy to do this also ...crises and economics makes us work twice as double time ... so i apologize for that
stay with me i have a good joke ....
Goldmund mimesis comes to the shop for repair ...strangelly havent been working with those ever again ...
The amp was serviced back home to mama in switzerland just a few days ago (owner has a brother traveling there ) anyway after come back owner happy trys to play with it works for a few minutes and then big boom and bad smell with a bit of smoke comes from it ....
then it comes to my shop where we actually found on of the main caps blown to the moon ( see att fotos ) said to myshelf that this worth looking at .... try to ind out why and how ...
my conclusion was that when goldmund choose to use PHILIPS capacitors ( but Japanese transitors ha ha ha ) that actually have very wierd pin spacing and 4 non compatible pins
that also means that the pcb canot use any other capacitor like a Nippon or anything else since pins do not fit
that also means that when capcitors replaced on service could be as wel from the same batch as from the original order made to create the amps ... hmmm that doesnt work very well since a 6-8 year old but other than that new capacitor is onot the best way to go
on the other hand it may aswell be just a faulty cap ... who knows
i moded the all thing ...i dont like philps parts and also neve rthought that 6800 mfd was enough for this amp so i go for 10.000 nipon with a small mod
all worked fine amp was working perfeclty all right and after some days developed some problem that sounded like a dry soldering which is a coomon problem around the hubrids of this amp .... amp was returned for more checks but since i felt kinda sorry for the costumer that has no amp for such a long time i said to him :
here !!! have this amplifier for a few days ( that will be the dual mono P3A presented in the begining of the thread ) .....
Big trouble !!!! costumer wants to buy the P3A ...trush the goldmund and have a second version to give as a present for his daughter ....keep in mind that the specific costumer is 50 years old ...a very sophisticated listener ...professor of physics with a highly sophisticated ...rest of a system....
enjoy some goldmund explosive fotos
havent been updating the thread for Quiet a long time ... sorry to say i am way to busy to do this also ...crises and economics makes us work twice as double time ... so i apologize for that
stay with me i have a good joke ....
Goldmund mimesis comes to the shop for repair ...strangelly havent been working with those ever again ...
The amp was serviced back home to mama in switzerland just a few days ago (owner has a brother traveling there ) anyway after come back owner happy trys to play with it works for a few minutes and then big boom and bad smell with a bit of smoke comes from it ....
then it comes to my shop where we actually found on of the main caps blown to the moon ( see att fotos ) said to myshelf that this worth looking at .... try to ind out why and how ...
my conclusion was that when goldmund choose to use PHILIPS capacitors ( but Japanese transitors ha ha ha ) that actually have very wierd pin spacing and 4 non compatible pins
that also means that the pcb canot use any other capacitor like a Nippon or anything else since pins do not fit
that also means that when capcitors replaced on service could be as wel from the same batch as from the original order made to create the amps ... hmmm that doesnt work very well since a 6-8 year old but other than that new capacitor is onot the best way to go
on the other hand it may aswell be just a faulty cap ... who knows
i moded the all thing ...i dont like philps parts and also neve rthought that 6800 mfd was enough for this amp so i go for 10.000 nipon with a small mod
all worked fine amp was working perfeclty all right and after some days developed some problem that sounded like a dry soldering which is a coomon problem around the hubrids of this amp .... amp was returned for more checks but since i felt kinda sorry for the costumer that has no amp for such a long time i said to him :
here !!! have this amplifier for a few days ( that will be the dual mono P3A presented in the begining of the thread ) .....
Big trouble !!!! costumer wants to buy the P3A ...trush the goldmund and have a second version to give as a present for his daughter ....keep in mind that the specific costumer is 50 years old ...a very sophisticated listener ...professor of physics with a highly sophisticated ...rest of a system....
enjoy some goldmund explosive fotos
Ultra P3A build
Hi Sakis and gang,
Here is a pic of my dual mono P3A.
I have upgraded almost everything compared to my old build of junk parts.
Some info:
300VA Talema 2X 25V toroidal transformer per channel.
44,000uF filtering per channel using Evox Rifa PEH 169 63V caps.
1.5uF Auricap for input.
4X Vishay 35A 400V bridge rectifiers per channel
CDE silver mica 500V caps for all the 100pF cap values
KOA 1/4 miniature 1% metal film resistors
Vishay 3% 0.33R emitter resistors
Matched BD546 / BD139/140 and 2SC5200 / 2SA1943
0.33 Deg C / watt heatsinks per channel
Bias current 50mA. (best treble response)
DC Offset - 11mV and 12.5mV for L and R channels respectively.
[Driven direct via PC as source]
This amp has the sonic profile of my dream amp. It is extremely hard to describe the sound character.
The most incredible deep and controlled bass I have ever heard from a speaker/amp combo.
I am using a pair of Vintage Goodmans XB35 speakers and all my mates swore I had left a sub on, hidden in the room.
Separation is phenomenal. Vocal clarity is pristine, pure without "grainyness".
Soundstage is ultra wide with imaging very sharply focused in the centre.
The amp begs to be driven hard and it doesn't break a sweat.
I thought my old P3A sounded extremely good in Malaysia, but here in NZ, it is on a whole new level.
This amp will drive my reference speakers once they are completed.
Sonic bliss at last.....
Hi Sakis and gang,
Here is a pic of my dual mono P3A.
I have upgraded almost everything compared to my old build of junk parts.
Some info:
300VA Talema 2X 25V toroidal transformer per channel.
44,000uF filtering per channel using Evox Rifa PEH 169 63V caps.
1.5uF Auricap for input.
4X Vishay 35A 400V bridge rectifiers per channel
CDE silver mica 500V caps for all the 100pF cap values
KOA 1/4 miniature 1% metal film resistors
Vishay 3% 0.33R emitter resistors
Matched BD546 / BD139/140 and 2SC5200 / 2SA1943
0.33 Deg C / watt heatsinks per channel
Bias current 50mA. (best treble response)
DC Offset - 11mV and 12.5mV for L and R channels respectively.
[Driven direct via PC as source]
This amp has the sonic profile of my dream amp. It is extremely hard to describe the sound character.
The most incredible deep and controlled bass I have ever heard from a speaker/amp combo.
I am using a pair of Vintage Goodmans XB35 speakers and all my mates swore I had left a sub on, hidden in the room.
Separation is phenomenal. Vocal clarity is pristine, pure without "grainyness".
Soundstage is ultra wide with imaging very sharply focused in the centre.
The amp begs to be driven hard and it doesn't break a sweat.
I thought my old P3A sounded extremely good in Malaysia, but here in NZ, it is on a whole new level.
This amp will drive my reference speakers once they are completed.
Sonic bliss at last.....
Attachments
Hi Pavel,
Thanks. Today I will set up your PRE3 preamp to drive the amp.
Sakis,
I adjusted the bias while the music was playing and noted that the bass got a fraction heavier at about 100mA. The difference is very very tiny and it took about 20 adjustments to confirm what I heard.
What did you find out when you adjusted the bias on your amp?
Also note that we are using different output transistors.
I used 2SC5200/2SA1943. The bass stuns me everytime with the precision of a watchmaker.
Thanks. Today I will set up your PRE3 preamp to drive the amp.
Sakis,
I adjusted the bias while the music was playing and noted that the bass got a fraction heavier at about 100mA. The difference is very very tiny and it took about 20 adjustments to confirm what I heard.
What did you find out when you adjusted the bias on your amp?
Also note that we are using different output transistors.
I used 2SC5200/2SA1943. The bass stuns me everytime with the precision of a watchmaker.
PRE 3 preamp by Pavel
The P3A amp is now being driven by Pavel's PRE3 preamplifier. I was dumbfounded as there was no sonic change when the preamp was introduced.
Did A/B testing for a couple of hours on mono tracks with level matched volumes but there was no difference. Bias is now set at 60mA - heatsinks are still cold to the touch. Ambient temp here is about 21 Deg.
I can only come to the conclusion that the preamp acted like a wire with gain (10X), capturing the essence of the P3A as purely as possible. To be honest, I wanted the preamp to add it's own flavour to the music...oh well =) This is the first preamp that I've built that didn't have any sound of it's own.
A pic of the messy setup. Amazingly there is not the slightest whisper of hiss from the 90dB tweeters.
The P3A amp is now being driven by Pavel's PRE3 preamplifier. I was dumbfounded as there was no sonic change when the preamp was introduced.
Did A/B testing for a couple of hours on mono tracks with level matched volumes but there was no difference. Bias is now set at 60mA - heatsinks are still cold to the touch. Ambient temp here is about 21 Deg.
I can only come to the conclusion that the preamp acted like a wire with gain (10X), capturing the essence of the P3A as purely as possible. To be honest, I wanted the preamp to add it's own flavour to the music...oh well =) This is the first preamp that I've built that didn't have any sound of it's own.
A pic of the messy setup. Amazingly there is not the slightest whisper of hiss from the 90dB tweeters.
